Integrated circuit including clip

ABSTRACT

A semiconductor device is provided that includes a leadframe, a die, and a clip. The leadframe has a flag and a power pad. The die is coupled to the flag. The clip comprises a die retaining section and a pad section. The die is coupled to the die retaining section, and the pad section extends from the die retaining section. The pad section is coupled to the power pad.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of Ser. No. 11/142,077 filed on May 31,2005.

FIELD OF THE INVENTION

The present invention generally relates to integrated circuits andpackaged integrated circuits, and, more particularly, to a method ofmaking an integrated circuit.

BACKGROUND OF THE INVENTION

An integrated circuit (“IC”) die is a small device formed on asemiconductor wafer, such as a silicon wafer and is typically cut fromthe wafer, coupled to a flag portion of a leadframe, and electricallyconnected to power pads of the leadframe via a wirebonding process. Thewirebonding process may also be used to cross connect bond pads of thedie or to cross connect other leads of the leadframe. The die, bondwires, and leadframe are then encapsulated and singulated from otherdice to form a single packaged device.

As technology has advanced, the demand has increased for ICs that aremore dense and that do not increase the size or footprint of thepackaged device. Additionally, the desire has remained for an increasednumber of inputs and outputs between the IC and leadframe power pads.Consequently, the densities of connections between the IC die and theleadframe has increased. To produce the desired devices, fine pitch andultra-fine pitch wire bonding have been utilized, and the bond wirediameters have decreased.

Although the aforementioned changes to the wirebonding technologies havebeen effective in producing operable ICs, they have certain drawbacks.For example, the decreased pitch and wire diameter may causedifficulties in the handling and the bonding of the bond wire. Inparticular, the bond wires may unintentionally short to other conductivestructures of the packaged device, such as other bond wires, pads,leads, or the die. The bond wires may be more susceptible to shortingduring IC die encapsulation as, for example, from “sweeping,” where theinjection or transfer of the liquid molding encapsulant may move thebond wires against other conductive structures. To decrease the shortingeffect, insulated or coated wires have been used; however, these typesof wires are difficult to bond to the bond pads. Some approaches havebeen used to remove a portion of the wire coating. But, the removalprocess may require additional equipment, which may increase productiontime and costs.

Accordingly, it is desirable to have a method for manufacturing an ICdie that is simple and cost-efficient to implement. Moreover, it isdesirable for the method to yield high quality devices with decreasedshorting effects. Furthermore, other desirable features andcharacteristics of the present invention will become apparent from thesubsequent detailed description of the invention and the appendedclaims, taken in conjunction with the accompanying drawings and thisbackground of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and

FIG. 1 is a cross-sectional view of an exemplary package device;

FIG. 2 is a top view of an exemplary leadframe having an exemplary powerdie and exemplary control die coupled thereto that may be implemented aspart of the package device depicted in FIG. 1;

FIG. 3 is a top view of an exemplary clip that may be implemented aspart of the semiconductor package depicted in FIG. 1;

FIG. 4 is a cross-sectional view of another exemplary embodiment ofpackage device;

FIG. 5 is a flow diagram of an exemplary method for manufacturing theexemplary package devices depicted in FIG. 1; and

FIG. 6 is a flow diagram of an exemplary method for manufacturing theexemplary package devices depicted in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the invention is merely exemplaryin nature and is not intended to limit the invention or the applicationand uses of the invention. Although the invention is shown embodied in aQuad Flat No-lead (QFN) type package, those of ordinary skill in the artwill readily understand the details of the invention and that theinvention is applicable to other package types. Furthermore, there is nointention to be bound by any theory presented in the precedingbackground of the invention or the following detailed description of theinvention.

FIG. 1 is a cross-sectional view of an exemplary embodiment of a singlepackage device 100. Package device 100 includes a leadframe 102, acontrol die 104, a power die 106, and a clip 108.

FIG. 2 is a top view of a section of an exemplary leadframe 102 havingpower die 106 and control die 104 coupled thereto. Leadframe 102includes a power pad 110, a power die flag 112, a control die flag 114,and a plurality of input/output connectors 116 each integrally formed.Power pad 110 is configured to be electrically coupled to anon-illustrated external power source to receive power therefrom. Inthis regard, power pad 110 may include a plurality of connectors 118. Itwill be appreciated that power pad 110 may have any one of numerousshapes, such as, for example, an elongated body, as shown in FIG. 2.

Power die flag 112 is configured to receive power die 106 and securespower die 106 thereto in any one of numerous conventional manners. Inone example, solder is used to couple power die flag 112 to power die106. Control die flag 114 is configured to receive control die 104. Thetwo are coupled to one another in any one of a number of manners, suchas, for example, in the same manner by which power die flag 112 andpower die 106 are coupled.

Input/output connectors 116 are configured to communicate signals froman external device to control die 104. In this regard, control die 104is electrically coupled to input/output connectors 116 using knowntechniques. In one exemplary embodiment, control die 104 andinput/output connectors 116 are wirebonded to each other via bond wires120, as shown in FIGS. 1 and 2. Control die 104 may receive signals tooperate power die 106 and, thus, is electrically coupled to power die106. For example, control die 104 may be wirebonded to power die 106 viabond wires 122. Bond wires 122 may be coupled to power die 106 through aplurality of bond pads 124.

Power die 106 is configured to provide power to device 100 for operationand thus, is electrically coupled to power pad 110. To this end, clip108 (FIGS. 1 and 3) is employed to electrically couple power die 106 andpower pad 110. FIG. 3 is a top view of clip 108 that includes a dieretaining section 126 coupled to a pad section 128. Clip 108 may haveany one of numerous configurations. In one exemplary embodiment, clip108 is configured such that die retaining section 126 is raised relativeto pad section 128, as shown more clearly in FIG. 1. In such case, dieretaining section 126 and pad section 128 preferably have an offset thatis substantially equal to the thickness of power die 106. Accordingly,die retaining section 126 and pad section 128 are connected to oneanother by an appropriately angled bridge 130. In another exemplaryembodiment, die retaining section 126 and pad section 128 are levelrelative to one another, as shown in FIG. 4. In such case, anappropriately configured spacer 132 may be placed between pad section128 of clip 108 and power pad 110.

Die retaining section 126 is configured to engage power die 106, suchas, for example, by means of a plurality of bond pads 134 (shown in FIG.2) formed on power die 106 and may have any one of numerous shapes. Forexample, die retaining section 126 may be a single flange or multipleflanges that extend from pad section 128. In one exemplary embodiment,as shown in FIG. 3, die retaining section 126 includes two flanges 136and 138 that extend from pad section 128. Pad section 128 is configuredto be coupled to power pad 110 and may have any suitable configuration.For example, as shown in FIG. 3, pad section 128 may be an elongatedbody configured to extend across power pad 110 (shown in FIG. 1)

Package device 100 may be manufactured in a number of ways. Oneexemplary embodiment of a manufacturing method 500 is depicted in FIG.5. A leadframe, a die, and a clip, such as, for example, those depictedin FIGS. 1-3 are obtained (step 502). The die is then coupled to a dieflag of the leadframe (step 504). A die retaining section of the clip isattached to the die (step 506), and a pad section of the clip is affixedto a power pad of the leadframe (step 508).

Step 502 may be performed in a number of ways. In one exemplaryembodiment, the leadframe, die, and clip are obtained from, such as, forexample, a separate manufacturer. In another embodiment, the leadframe,die, and clip are manufactured as part of method 500 in any conventionalmanner.

After step 502, the die is coupled to the die flag. In one exemplaryembodiment, solder is deposited onto the die flag of the leadframe andthe die is placed onto the deposited solder (step 504). Step 504 mayalso include the step of coupling a second die to the leadframe andcoupling the second die to the first die. For example, the first die maybe a power die and the second die may be a control die. In such anembodiment, solder is deposited onto a power die flag of the leadframeand a control die flag of the leadframe, and the power die is placedover the power die flag while the control die is placed over the controldie flag. The control die is then coupled in a conventional manner toinput/output connectors formed on the leadframe and to bond pads formedon the power die, such as, for example, by wirebonding.

Then, the die retaining section of the clip is attached to the die (step506), and the pad section of the clip is affixed to the power pad (step508). These steps may include depositing solder onto the die, depositingsolder onto the power pad, and contacting the die retaining section andthe pad section of the clip to the deposited solder. It will beappreciated that steps 506 and 508 may be performed simultaneously or inany order. For example, solder may be deposited simultaneously onto thedie and the power pad, or in succession. Similarly, the die retainingsection and the pad section may be contacted with the deposited soldersimultaneously or in succession.

Step 506 may additionally include the step of applying a coating to thedie that facilitates soldering. This step may be performed before thesolder is deposited. The coating may be any one of numerous conductivematerials that provides the die with a wettable surface. In oneexemplary embodiment, the coating is three layers and includes aluminum,nickel deposited over the aluminum, and a gold flash over the nickel.

To ensure that the die retaining section and the pad section are fixedto the device, a reflow process may be performed after steps 506 and508. For example, the device may be heated to a temperature that isabove a melting point temperature of the solder to melt the solder andprovide bonds between the clip, die, and leadframe.

FIG. 6 illustrates another exemplary method 600 of manufacturing packagedevice 100. Here, a leadframe, a die, a clip, and a spacer, such as, forexample, those depicted in FIGS. 2-4 are obtained (step 602). The die iscoupled to the die flag of the leadframe (step 604). The spacer isplaced over the power pad (step 606). The die retaining section of theclip is attached to the die (step 608). The pad section of the clip isaffixed to the spacer (step 610).

Steps 602 and 604 may be performed in substantially the same manner asstep 502 and 504, respectively. Step 606 may be performed in anysuitable manner. For example, in one exemplary embodiment, step 606includes the steps of depositing solder onto the power pad andcontacting the spacer with the deposited solder. After step 606 isperformed, the die retaining section of the clip is attached to the die(step 608), and the pad section of the clip is affixed to the spacer(step 610). These steps may include depositing solder onto the die,depositing solder onto the spacer, and contacting the die retainingsection and pad section to the deposited solder. It will be appreciatedthat the steps 608 and 610 may be performed simultaneously or in anyorder. For example, solder may be deposited simultaneously onto the dieand spacer, or in succession. Similarly, the die retaining section andspacer may be contacted with the deposited solder simultaneously or insuccession. Additionally, a reflow process, similar to the processdescribed above in method 500, may be performed after steps 608 and 610to melt the deposited solder so that the clip, die, spacer, andleadframe are sufficiently attached to one another.

There has now been provided a semiconductor device that includes aleadframe, a die, and a clip. The leadframe has a flag and a power pad.The die is coupled to the flag. The clip comprises a die retainingsection and a pad section. The die is coupled to the die retainingsection, and the pad section extends from the die retaining section. Thepad section is coupled to the power pad. In one exemplary embodiment,the die retaining section and the pad section are level relative to oneanother and the device further comprises a spacer disposed between thepad section of the clip and the power pad. The spacer may have athickness that is substantially equal to a thickness of the die. Inanother exemplary embodiment, the die retaining section and the padsection of the clip are not level relative to one another and arecoupled to one another by an angled bridge.

In still another exemplary embodiment, the die retaining sectionincludes a first flange and a second flange, and the first flange andthe second flange each extend from the pad section. In another exemplaryembodiment, at least one of the leadframe and the clip comprises copper,nickel, palladium, and gold. In yet another exemplary embodiment, thedie includes a coating comprising aluminum, nickel, and gold.

In another exemplary embodiment, a method is provided of forming asemiconductor device from a die, a leadframe having a flag and a powerpad each integrally formed, and a clip having a die retaining sectionextending from a pad section. The method includes the steps of couplingthe die to the flag, attaching the die retaining section of the clip tothe die, and affixing the pad section of the clip to the power pad. Inanother exemplary embodiment, the step of coupling comprises depositingsolder on the flag and contacting the die to the deposited solder. Instill another exemplary embodiment, the step of attaching comprisesdepositing solder on the die and contacting the die retaining section ofthe clip to the deposited solder. In yet another exemplary embodiment,the step of affixing comprises depositing solder on the power pad andcontacting the pad section of the clip to the deposited solder. In stillyet another exemplary embodiment the steps of coupling, attaching, andaffixing each comprise the steps of depositing solder. In anotherexemplary embodiment, the method includes melting the solder to couplethe die to the leadframe, the die retaining section of the clip to thedie, and the pad section of the clip to the power pad.

In another exemplary embodiment, a method is provided of forming asemiconductor device from a die, a leadframe having a flag and a powerpad each integrally formed therein, a spacer, and a clip having a dieretaining section extending from a pad section. The method includescoupling the die to the flag, placing the spacer of the spacer leadframeover the power pad, attaching the die retaining section of the clip tothe die, and affixing the pad section of the clip to the spacer. In oneexemplary embodiment, the step of coupling comprises depositing solderon the flag and contacting the die to the deposited solder. In anotherexemplary embodiment, the step of placing comprises depositing solder onthe power pad and contacting the spacer to the deposited solder. Instill another exemplary embodiment, the step of attaching comprisesdepositing solder on the die and contacting the die retaining section ofthe clip to the deposited solder. In still another exemplary embodiment,the step of affixing comprises depositing solder on the power pad andcontacting the pad section of the clip to the deposited solder. Inanother exemplary embodiment, the steps of coupling, placing, attaching,and affixing each comprise the steps of depositing solder. In still yetanother exemplary embodiment, the method includes melting the solder tocouple the die to the leadframe, the spacer to the power pad, the dieretaining section of the clip to the die, and the pad section of theclip to the spacer.

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention, it being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims and their legal equivalents

1. A semiconductor device, comprising: a leadframe having a flag and apower pad; a die coupled to said flag; and a clip, comprising: a dieretaining section coupled to said die; and a pad section extending fromsaid die retaining section, said pad section coupled to said power pad.2. The semiconductor device of claim 1, wherein said die retainingsection and said pad section are level relative to one another.
 3. Thesemiconductor device of claim 2, wherein the device further comprises aspacer disposed between said pad section of said clip and said powerpad.
 4. The semiconductor device of claim 3, wherein said spacer has athickness that is substantially equal to a thickness of said die.
 5. Thesemiconductor device of claim 1, wherein said die retaining section israised relative to said pad section.
 6. The semiconductor device ofclaim 5, wherein said clip further comprises an angled bridge couplingsaid die retaining section to said pad section.
 7. The semiconductordevice of claim 1, wherein said die retaining section comprises a firstflange and a second flange, said first flange and said second flangeeach extending from said pad section.
 8. The semiconductor device ofclaim 7, wherein said die comprises a first row of bond pads and asecond row of bond pads, and wherein said clip is positioned such thatsaid first flange overlies said first row of bond pads and said secondflange overlies said second row of bond pads.
 9. The semiconductordevice of claim 1, wherein at least one of said leadframe and said clipcomprises copper, nickel, palladium, and gold.
 10. The semiconductordevice of claim 1, wherein said die includes a coating comprisingaluminum, nickel, and gold.
 11. A semiconductor device, comprising: aleadframe having a flag and a power pad; a power die having an uppersurface and a lower surface, said lower surface coupled to said flag,and said upper surface having a plurality of bond pads thereon; and aclip electrically coupling said power pad to said power die, said clipcomprising: a die retaining section bonded to said upper surface of saidpower die and electrically coupled to said plurality of bond pads; and apad section bonded to said power pad.
 12. The semiconductor device ofclaim 11, wherein said power die flag is substantially adjacent saidpower pad.
 13. A semiconductor device according to claim 11, furthercomprising a spacer coupled between said pad section and said power pad.14. A semiconductor device according to claim 13, wherein said spacerhas a thickness substantially equivalent to the thickness of said powerdie.
 15. A semiconductor device according to claim 11, wherein said clipfurther comprises an angled bridge joining said die retaining section tosaid pad section.
 16. A semiconductor device according to claim 11,wherein said die retaining section comprises a flange.
 17. Asemiconductor device according to claim 16, wherein said flange has alength substantially equivalent to the length of said power die.
 18. Asemiconductor device according to claim 16, wherein the longitudinalaxis of said flange is generally perpendicular to the longitudinal axisof said pad section.
 19. A semiconductor device according to claim 11,wherein pad section comprises an elongated body having a lengthsubstantially equivalent to the length of said power pad.
 20. Asemiconductor device according to claim 11, wherein said power diecomprises multiple rows of bond pads, and wherein said die retainingsection comprises a plurality of flanges each bonded to a different oneof said multiple rows of bond pads.